In an earlier thread I had questions about the distribution block, well I replaced the block, rear wheel cylinders, rubber hoses only to find out there was no fluid coming from the rear of the new and/or old master cylinder. I have bench bled the master cylinder 4 times and reinstalled the master cylinder but still no fluid. I don't see any adjustment on the push rod. It's odd to me that both master cylinders have the same issues. There was good flow while the master cylinder was in the vice. What am I missing? Thanks

 

Sounds like the "distribution block" has a ............blockage. I seem to recall reading in another thread here that some "distribution blocks" have an internal piston that can get de-centered and will block either the front or rear passageway. I'm pretty sure Joe P. posted a photo of the tool that he uses to re-center it.

 

You need to check the pushrod adjustment where the rod goes into the master. You can find the procedure in the chassis service manual.

 

The distribution block has been replaced but the problem is the fluid is not leaving the the rear bowl of the new and old master cylinder. I too think the problem is the pushrod but there is no adjustment, it rotates but no in or out adjustment. I tried adding more gaskets between the master cylinder and booster but that did not help. Thanks for the responses.

 

The clevis is located in the bottom hole on the brake pedal for power brakes and the top hole for manual brakes. Do you have that correct for your application?

 

Yes the clevis is located in the bottom hole as it should be. Thanks

 

In your first post you stated that "I have bench bled the master cylinder 4 times". How do you bleed the rear portion of the MC without fluid coming out of the rear port? Seems that would exonerate the MC and point towards the distribution block.

 

Interesting thread. I'm in the process of replacing the MC on my 71 98. When I did it in the past I was able to bench bleed the MC without any problems and then it bled normally when I installed it.

Make sure you paint the MC and vacuum booster with brake fluid resistant paint. This is the kit I used. Good luck!

https://www.summitracing.com/parts/p...SABEgKapPD_BwE

 

I loosened the master cylinderalmost all the way from the booster and the system worked as it should. The pushrod appears to be original so should I shorten it?

 

What does the back of the M/C look like? Specifically is it a deep hole or a shallow one in the end of the piston? Or, do you possibly have one of the M/C setups with the optional spacer that accommodates both styles?

 

Ah, OK, I'm following now. The theory is that when the MC is bolted to the booster, the pushrod is pushing the MC piston too far so that when you step on the pedal, not enough piston travel is left (before bottoming out in the MC) to push any more fluid out the rear port. I think Joe is onto a solution.

 

Joe, the rear of the m/c has a deep hole.

 

Well, then the only options are that the pushrod to the brake pedal is adjusted incorrectly or the booster is assembled incorrectly.

 

OK, the front and rear wheel cylinders have been bleed, brake shoes adjusted and still absolutely no brakes. This beautiful car is going to the junk yard. I have been working on cars for over 60 years and have never seen any thing like this. I appreciate every ones help.

 

What does "no brakes" mean? No pressure on the brake pedal? How did you resolve the problem with the pushrod on the booster? The M/C has a compensating port that is uncovered when the internal piston is fully released to allow fluid from the reservoir into the brake system. Once the pedal is pressed, the piston closes off this compensating port so you can build pressure in the system. If the piston is not in the correct position (pushrod either too long or too short), the M/C won't function properly.

How about we back up. Is this the original booster or did it come with the disc brake kit? If original, did you compare the depth of the hole in the new M/C to the one in the old one? If the booster is new, did you compare the position of the pushrod in the new one with the pushrod on the original?

 

Does the power booster have the long push pin to fit the deep hole?? Can you post a picture of both the rear of the master cylinder and the front of the power booster pin that mates to the master?

 

I did not change the booster and it appears to have been on the car for a long time. I backed off the push rod the same distance I loosened the m/c from the booster and then retightened the m/c. The pedal is firm as it should be and no air is coming from the new wheel cylinder bleeders just fluid but the car will not stop rolling. Even if the booster isn't working as it should I would think the brakes should stop the car. The car has drum brakes all around, I have not tried to do a disc brake conversion. Thanks for your patience, mine is getting really thin. I am unable to post any pictures.

 

There are so many threads with brake bleeding problems that I have trouble keeping them straight. To recap: you have a four wheel power drum car and only replaced the M/C? What was the reason for the replacement? Where did you get the new M/C? What else if anything was changed?

 

I changed the m/c because I was not getting any fluid to the rear w/c. The brake light was on in the dash so I changed the distribution block too. The changes I made did not change anything. The new and the old m/c had the deep tapered hole at the rear. I just removed the push rod from the booster to the m/c and it is the long one at 3 15/16 inches but it is blunt and not tapered. My question is should I shorten the push rod to 2 9/16 inches which is the correct length for the short push rod? Thanks

 

If there was no fluid to the rear before and only changing the M/C made no difference, then the problem is not the M/C or booster. And if you have a deep hole in the M/C, do NOT cut the pushrod.

How about backing up. If you just bolt the M/C to the booster and make up short "U" tubes that run from the outlet ports back into the reservoir, what happens? Does fluid come out of both of them?

 

By loosening the m/c from the booster and pulling it away approximately 3/8 inch I was able to get fluid to the rear brakes so I think the problem is push rod length, I was not able to correct the problem by adjusting the push rod at the brake pedal. The booster looks to be as old as the car so I'm ordering a new one and start over. Thanks

 

The rear pushrod is to adjust for pedal height, nothing more. It sounds like you have a mismatched MC to power booster by your description.

 

^^x2^^